1. Field Of The Invention
This invention relates to flapper valves, and more particularly, to a valve with a flapper having a protective hinge or pivot pin sleeve for reducing wear on the flapper.
2. Description Of The Prior Art
Drillable flapper valves have been used for many years in a variety of applications, such as in the oil industry as a means for preventing backflow of displaced well fluids. The life of flapper valves is generally shorter than other types of float equipment check valves, such as poppet valves and ball valves, because of wear on the flapper.
Historically, the flappers in floating equipment flapper valves have been made from materials such as cast iron or aluminum alloys. Cast iron valves have a shortcoming in that they are inherently brittle. This is detrimental because accessory equipment sometimes requires an activating ball to be pumped at high rates past the valve. The impact is such that it may shatter the cast iron hinge portion causing not only a check valve failure but also other tool or job failures therebelow. Aluminum valves have been used because they are more ductile and better resist impact. However, when used over extended periods, aluminum hinges wear due to the cycling caused by pump strokes. This wear occurs around a hinge or pivot pin, generally made of steel, which holds the flapper in place. The obvious consequence of this wear is potential flapper failure and again, possible failure of equipment below the flapper valve.
The present invention which utilizes protective hinge or pivot pin sleeve means greatly reduces the wear to the flapper by providing a bearing surface between the flapper hinge or ear portion and the hinge or pivot pin. The protective sleeve which is made of a suitably hard material is installed as an integral part of a flapper assembly and thereby rotates with the flapper on the hinge pin. Because the sleeve can be made of a material relatively harder than the flapper, aluminum flappers may still be used to take advantage of their ductility and resistance to impact.
In addition to floating equipment flapper valves, the present invention is applicable to any other type of flapper valve.